1. Technical Field
The present disclosure generally relates a method for manufacturing a curved glass sheet and a mold employed in the same.
2. Description of Related Art
Curved or bent glass sheets are commonly employed as glazing closures in vehicles such as automobiles. Such curved or bent glass sheets are conventionally generally produced by gravity bending methods. The commonly used method for manufacturing the curved or bent glass sheet includes the steps of gravity bending a glass sheet at elevated temperature on a gravity bending mold in a gravity bending zone of a furnace. Later, the gravity bent glass sheet is being press bent to a desired shape with an upper mold while the glass sheet is supported by the gravity bending mold as a lower mold in a press bending zone of the furnace. The ambient temperature in the press bending zone is thereby controlled to control the cooling rate of the glass sheet in the press bending zone.
However, in recent years, the developments in vehicle design have required curved or bent glass sheet of complex curvature and lower roughness. It is impossible to impart more than a very limited degree of complex curvature to a sheet of glass by gravity bending alone. Furthermore, the use of automated assembly by vehicle manufacturers demands that the glass meets tighter dimensional tolerances. The shape of the periphery of the bent glass pane must be accurate, not only in terms of its two dimensional projection, but also in three dimensions, i.e. the angle of the glass adjacent at the periphery must be correct. These requirements, in conjunction with the trend towards deeper and more complex bends, can no longer be met by glass that is bent by the gravity bending technique alone.
Therefore, there is room for improvement within the art.